Hi Eileen, If I understand correctly, you are interested in processing the pressure and flow rates at the outflows of your 3D model which connect to RCR elements, in order to tune your boundary conditions. For simulations with RCR boundary conditions, simvascular generates PHistRCR.dat and QHistRCR....

It's been my experience with the volume render that it doesn't handle vector quantities as a scalar magnitude, as one would want. You need to explicitly give the volume render scalar variables. To confirm this, can you check if the calculated mag(Velocity) and velocity vector magnitude give identica...